This is primarily aimed at people who live above 4,000 feet. It's a question of gas. Does everyone keep using 87 octane during the winter or do you switch to 85? My fuel economy is dropping more than it usually does in the winter, and I'm still using 87 octane. Any suggestions?
I think that some companies are putting in more ethanol than they used to - and I know that my car doesn't respond well to it. I try to use fuels that either advertise having no or very little ethanol (although most around here simply say "up to 10%"). If there's another brand available, try it and see how it responds.
I'm not in a "high altitude" area myself, but the car I drove through the mountains the last time seemed to require higher octane fuel to prevent pinging - not lower. Around here, my Sunfire also responds well to higher octane. It will even start to ping lightly now on 87 when accelerating moderately (although this is only since I had the head shaved a couple of years ago, raising compression beyond stock).
We don't have any gasoline offered below 87 octane here. Currently 91 octane is an additional 12 cents/litre (about 45 cents per gallon) more than 87 - I sure wish my car would be happier with the 87. Fortunately it's not bad on gas (averaged 31 miles per U.S. gallon on my last tank with about 1/3 city driving), so it doesn't affect me too badly. The premium I'm using is from Shell which contains NO ethanol - that's the fuel it seems happiest with. By comparison, on a tank I bought from Pioneer (87 octane with ethanol) I only averaged 27 with mostly highway driving. It also performs much more nicely with the 91 as a nice side bonus (especially when towing in the summer). In the summer I managed to hit a record of 40 a couple of times with the Shell 91 (straight highway). I'm very sure I wouldn't have achieved that number if there was any ethanol in there.
Hopefully someone else with more experience in the high altitudes can respond here. Now I'll have to find an excuse to take my Sunfire on a long trip to see what it does up there...
John
